Speaker
Description
Coverings made of technical fabrics are a solution eagerly used by engineers to cover a large area without the need for intermediate supports. They are mainly made of two types of composites: polyester threads coated with PVC and fiberglass threads coated with Teflon. Manufacturers of both types of fabrics guarantee their durability for 10 and sometimes even 50 years. However, coverings made of such fabrics sometimes work in difficult environmental conditions. An example of this can be the membrane hanging roof of the Forest Opera in Sopot (glass threads – erected in 2012) or the road salt warehouse near Wejherowo (polyester threads – erected in 2022). In the first case, especially in summer, the fabric is exposed to high temperatures, while in the second case, it is exposed to an aggressive environment (moisture with a high salt content).
After several years of operation, both roofs failed. In the Forest Opera covering, under the influence of a heavy snow load in February 2021, one of the segments of the roof cover was torn. The roof of the warehouse near Wejherowo was completely destroyed after just one year of operation in the winter of 2023. In order to determine the causes of the failure, tests of the mechanical properties of the technical woven fabric from which they were made were carried out. In the case of the Forest Opera, tests of the strength of the fabric were also carried out before the covering was made. In the case of the covering near Wejherowo, only the data of the fabric manufacturer was available.
In the case of the coated woven fabric used in the Forest Opera, a decrease in the load-bearing capacity of the fabric was found to be up to 30\%. It was determined that in addition to the decrease in the load-bearing capacity of the fabric, the cause of the failure was the accumulation of snow in the lower part of the destroyed segment.
In the case of the warehouse near Wejherowo, no significant decrease in load capacity was found. It was established that the cause of the disaster were serious errors in the design of the roofing, and the direct cause of the failure was the destruction of the steel beams with which the roof was tensioned.
During the presentation, the results of laboratory tests and finite element calculations of both coverings were shown.
